27th November 2023

NOTAM Understanding

Initial Report

[Airport] have recently seen an increase in controlled airspace infringements. As a result of investigations and ongoing analysis, it has become apparent that this is at least in part due to an increase in pilots operating under the misapprehension that our airspace was closed (NOTAM’d deactivated). A common theme amongst a few of them is the use of ‘third-party software’ as an assist to flight briefing and navigation, and a failure to properly understand and assess the information displayed under the NOTAM tab.

For example, during the month of June, [Airport]’s Class D CAS was de-activated daily between 2000-0530Z. When issuing a longer-term NOTAM covering set daily closure periods such as this, the NOTAM Office require us to issue the NOTAM from the 1st-30th, with a daily schedule for the closure periods, as opposed to a separate NOTAM for each day.

We have approached the manufacturer of one such popular provider, who were most accommodating in their response. It seems that all information is readily available for the pilot. The problem seems to be the pilot’s interpretation of the information displayed. On investigation, it seems that an easy mistake for the pilot to make is to read the headline ‘Deactivated by NOTAM from X to Y’ and either misread, don’t understand, or fail to notice, the ‘Schedule’. They have the option to ‘touch for more details’, which opens the full NOTAM text in another box, but either this is not being done, or again the ‘schedule’ part is misunderstood.

The purpose of this email is to ask, via the medium of CHIRP, that pilots using popular third-party systems as a navigation/flight briefing aid, are made aware of the need to fully interrogate NOTAM information as presented to them on a digital display, especially the ‘schedule’ part, and to be made aware of its purpose and meaning.

Basically speaking, if ATC are operating, it’s best to assume that the CAS is also active. Always call in good time and ask, irrespective of what you believe the NOTAM says. If asked to stand-by, or no clearance is received, route around and avoid – operate under the assumption that CAS is active unless confirmed otherwise by ATC/ATIS. ATC are obliged to MOR every incursion, however minor. This includes those where mode ‘C’ indicates inside but the pilot reports outside.

Please don’t rely on the summary page of nav-aid without question – it is no defence against the MOR!

CHIRP Comment

The report highlights the need for pilots to read all information within NOTAMs and not just take a cursory approach to acknowledging their presence from the title – this includes expanding all the NOTAM information to properly absorb its contents. That being said, some NOTAM titles are not helpful in themselves because they can give a misleading impression as to their content.

For example, A NOTAM title such as ‘Notamville Airport CAS deactivation times 0900-1700’ intended to draw peoples’ attention to various times between 0900-1700 would probably be better titled as ‘Notamville Airport CAS deactivation schedule’ because this would then indicate that there was more information to be gleaned than simply reading the title and wrongly assuming the CAS was deactivated from 0900-1700.

Although the report was a plea from a particular airfield, it has widespread relevance in reminding us all that there are often details within NOTAMs that may not be apparent at first glance: those compiling NOTAMs can help by thinking about how they make sure that readers are effectively pointed towards the information they need; and readers need to fully read NOTAMs to make sure that they access the complete details.

Key Issues relating to this report

Dirty Dozen Human Factors

The following ‘Dirty Dozen’ Human Factors elements were a key part of the CHIRP discussions about this report and are intended to provide food for thought when considering aspects that might be pertinent in similar circumstances.

  • Resources – potential ambiguity in NOTAM titles
  • Knowledge – full NOTAM information not accessed
  • Complacency – assumption that NOTAMs do not need to be fully read
  • Complacency
  • Knowledge
  • Resources

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